Fire-Retardant Characteristics of Water-Blown Molded Flexible Polyurethane Foam Materials

Abstract

Polyurethane flexible foam materials have a wide range of industrial applications. These applications include flexible foams for packaging, polyurethane-based foam materials for seat cushions in buses, railways, the airline industry, prisons, and domestic bedding. There is a substantial need for the development of flexible molded foam materials with low heat release rates and smoke release rates. In this study, an extensive series of flexible, molded polyurethane seat cushion materials based on polymeric MDI and polyether polyols were prepared and further modified with commercially available flame retardant additives. The flame retardant behavior of these foam materials was evaluated using Cone Calorimeter (ASTM-E 1354), vertical Bunsen burner test for cabin and cargo component materials [FAR 25.853 (a), Appendix F, Part I, (a)(1)(i) and (a)(1)(ii)], and oil burner test for seat cushions [FAR 25.853 (c), Appendix F, Part II]. Several formulations that passed the 12-second vertical Bunsen burner test were identified. These include the formulations modified with Firemaster® HP-36, Decabromodiphenyl oxide/antimony oxide/Firemaster®HP-36, Fyrol® FR-2, and Fyrol® FR-2/graphite powder. A formulation modified with Antiblaze®-230 and a cross-linking agent passed both 12-second and 60-second vertical Bunsen burner tests. But, all of these materials did not pass the oil burner tests for seat cushions. Using the cone calorimeter, materials with a reduction in peak heat release rate of up to 57% were prepared and with up to a fourfold increase in char residue in the cone. However, most FR formulations showed an increase in carbon monoxide and smoke generation. Lowest peak HRR data were obtained with Firemaster® HP-36/Sb2O3 and Dow Silicones®1-9641 at 25kW/m2 and with Fyrol® FR2/cross-linker at 35 kW/m2 exposure. It appears that there is no correlation between cone calorimeter results and vertical Bunsen burner test results.